Semiconductor integrated circuit device

ABSTRACT

A semiconductor integrated circuit device provided with a first circuit block BLK 1,  a second circuit block DRV 1  and a conversion circuit MIO 1  for connecting the first circuit block to the second circuit block. The first circuit block includes a first mode for applying a supply voltage and a second mode for shutting off the supply voltage. The conversion circuit is provided with a function for maintaining the potential of an input node of the second circuit block at an operation potential, thereby suppressing a penetrating current flow when the first circuit block is in the second mode. The conversion circuit (MIO 1  to MIO 4 ) are commonly used for connecting circuit blocks.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor integrated circuitdevice, particularly to a semiconductor integrated circuit device thatoperates at a high-speed and yet is energy efficient.

2. Description of the Related Art

A fine microelectronic fabrication technique (fine-fabrication,hereafter) is widely employed in processing chips in order to integratemany functions on a single chip, as described in “Deep-SubmicronMicroprocessor Design Issues”, IEEE Micro, pp. 11-22, July/August, 1999.This fine-fabrication enables many MOS transistors to be integrated on achip, thereby providing the chip with many functions.

To efficiently integrate many circuits on a chip with fewer defects,however, demands many number of man-hours, namely a long period fordeveloping a plan for such chip. To the contrary, in order to shortenthe development period by increasing the number of man-hours causes ashortage of human resources required for designing, thereby causing abottleneck in designing other types of chips. To solve this dilemma,diversion of developed circuit blocks to other types of chips has beenexamined.

On the other hand, it is well known that a leakage current (the leakagecurrent includes a sub-threshold leakage current, a gate tunnel leakagecurrent and junction leakage currents such as a GIDL (Gate-Induced DrainLeakage) current) increases due to the fine-fabrication of chipprocesses. This is described in “Identifying defects in deep-submissionCMOS ICs” IEEE Spectrum, pp. 66-71, 1996. Those leakage currents causethe power consumption of a chip to increase. Controlling the supplyvoltage of a circuit block in its standby state enables the powerconsumption to be reduced.

Shutting off the supply voltage to the circuit block in the standbystate, however, allows the circuit block output node to go into afloating state, causing a penetrating current (short circuit current) toflow in another circuit block that receives the output from the outputnode. When the circuit block whose supply voltage is controllable is toalso be used for another chip, an interface circuit must be designed soas to prevent penetrating currents. This might be an obstacle for re-useof low power-driven circuit blocks.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a semiconductorintegrated circuit device that solves the above-mentioned problems.

In order to achieve this object, one aspect of the present invention isdirected to a semiconductor integrated circuit device that includes afirst circuit block, a second circuit block, and a conversion circuitfor connecting the first circuit block to the second circuit block, thefirst circuit block having a first mode for receiving a supply voltageand a second mode for shutting off the supply voltage, wherein when thefirst circuit block is in the second mode, the conversion circuitcontrols the potential of an input node of the second circuit block toany of the operating potentials of the second circuit block. Inparticular, the conversion circuit, which is provided with a commonpower supply control interface, connects each circuit block to anotherthrough itself.

In another aspect, the semiconductor integrated circuit device provideda power line around each circuit block and disposes a power controllingcircuit properly in an area where the power line is disposed.

These and other objects, features and advantages of the presentinvention will become more apparent in light of the followingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a semiconductor integrated circuit deviceof a basic embodiment of the present invention;

FIG. 2 is another block diagram of the semiconductor integrated circuitdevice of the present invention;

FIG. 3 is a basic block diagram of the semiconductor integrated circuitdevice of the present invention, which includes a micro-scale I/Ocircuit;

FIG. 4 is a block diagram of two circuit blocks that might havedifferent supply voltages and micro-scale I/O circuit provided betweenthose two circuit blocks;

FIG. 5 is a block diagram of the micro-scale I/O circuit for enablingthe normal operation in a first case of power control;

FIG. 6 is a block diagram of the micro-scale I/O for enabling the normaloperation in first and second cases of power control;

FIG. 7 is a block diagram of the micro-scale I/O circuit for enablingthe normal operation in first and third cases of power control;

FIG. 8 is a block diagram of the micro-scale I/O circuit for enablingthe normal operation in first, second, and third cases of power control;

FIG. 9 is a detailed block diagram of the micro-scale I/O circuit shownin FIG. 8;

FIG. 10 is a chart for describing a relationship between input/outputsignals to/from the micro-scale I/O circuit shown in FIG. 9;

FIG. 11A is a block diagram of an interface of a power switchingcontroller circuit;

FIG. 11B is a timing diagram corresponding to FIG. 11A;

FIG. 12 illustrates connections of substrate terminals of a MOStransistor of a circuit block;

FIG. 13 illustrates other connections of the substrate terminals of aMOS transistor of a circuit block;

FIG. 14 is a layout (floor plan) of a circuit block;

FIG. 15 illustrates a power supply network of a circuit block;

FIG. 16 is a cross sectional view of a circuit block and a micro-scaleI/O circuit;

FIG. 17 is a layout (floor plan) of deep N-type wells of circuit blocksand a micro-scale I/O circuit;

FIG. 18 is a basic block diagram of the semiconductor integrated circuitdevice of the present invention, which includes micro-scale I/O circuitsprovided with a scanning function respectively; and

FIG. 19 is a configuration example of a level conversion circuit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

FIG. 1 shows a basic block diagram of the semiconductor integratedcircuit device of the present invention. Each of circuit blocks BLK1 andBLK2 includes one or more MOS transistors. In this specification, “MOStransistor” is used as generic term for insulated gate field effecttransistor but not limited thereto. The circuit block BLK shouldpreferably be composed as a CMOS circuit in which P-type and N-type MOStransistors are connected in series. The supply voltage of the circuitblock BLK1 is controlled so as to reduce a leakage current independentlyof the state of the power to the whole chip CHP1 (the circuit block BLK2may also be controlled). The configuration of each micro-scale I/Ocircuit MIO1 to MIO4 is specific to the present invention. The detailsof the configuration will be described later. An I/O buffer IOB1 isconfigured by a low impedance output driver circuit DRV1 used to drive alarge load capacitance outside a module MDL1, an input buffer circuitIBF1 having an electrostatic discharge (ESD) protection element, andother elements. An I/O buffer IOB2 also has the same configuration asI/O buffer IOB1. The I/O buffer MIOB1 is configured by an output drivercircuit DRV2 having a low impedance (higher than the output impedance ofthe output driver circuit DRV1 of the I/O buffer IOB1) used to drive acomparatively large load capacitance outside the chip CHP1 within themodule MDL1, an input buffer circuit IBF2 provided with an electrostaticdischarge (ESC) protection element as needed, and other elements. An I/Obuffer MIOB2 also has the same configuration with the I/O buffer MIOB1.In this specification, an I/O buffer used for the connection betweenchips in a module will be referred to as a “mini-scale I/O buffer” whenit is distinguished from an I/O buffer used for the connection betweenmodules. Reference symbols L11 to L13, L21 to L24, L31 to L32, and L41to L43 denote signal lines.

A chip is a semiconductor integrated circuit device that employs onesemiconductor substrate. A module is a semiconductor circuit deviceconfigured by one or plurality of chips. Examples of the module are, forexample, a stacked CSP (Chip Scale Package) and an MCP (Multi ChipPackage) in which a plurality of chips are mounted in one package. AnMCM (Multi Chip Module) and a SIMM (Single Inline Memory Module) usedwidely as dynamic memories are other examples of the module, in which aplurality of packages are mounted on one printed board.

A signal line group L41 is connected to the I/O buffer IOB1 through asignal line group L42 and a micro-scale I/O circuit MIO1. The signalline group L41 is eventually connected to a device outside a module MSL1through a signal line group L43. A signal line group L32 is connected tothe circuit block BLK2 through a micro-scale I/O circuit MIO4 and asignal line group L31. A signal line group L11 is connected to the I/Obuffer IOB2 through a micro-scale I/O circuit MI02 and a signal linegroup L12. The signal line group L11 is eventually connected to a deviceoutside the module MSL1 through a signal line group L13. A signal linegroup L21 is connected to a mini-scale I/O buffer MIOB1 through amicro-scale I/O circuit MI03 and a signal line group L22. The signalline group L21 is eventually connected to a mini-scale I/O buffer MIOB2located in the chip CHP2 in the same module as the chip CHP1 through asignal line group L23.

Each of the signal line groups L11, L12, L21, L22, L31, L32, L41 and L42includes signal lines specific to the corresponding circuit (circuitblock BLK or I/O buffer IOB(MIOB)) and power control interface signallines, respectively. Although not limited specifically, data signallines and address signal lines are included as the signal lines of thesignal line groups. Details of each power control interface signal lineswill be described later.

FIG. 2 shows another block diagram of the semiconductor integratedcircuit device of the present invention. Circuit block BLK1 is the samein function as the circuit block BLK1 shown in FIG. 1. Reference symbolsMIO1 and MIO4 denote micro-scale I/O circuits and reference symbols IOB1and IOB3 denote I/O buffers. Reference symbols CHP3 and MDL2 denote achip and a module, respectively. A signal line group L41 is connected toan I/O buffer IOB1 through a signal line group L42 and a micro-scale I/Ocircuit MIO1. And the micro-scale I/O circuit MIO1 is connected to adevice outside the module MDL2 through a signal line group L43. A signalline group L32 is connected to an I/O buffer IOB3 through a signal linegroup L31 and a micro-scale I/O circuit MIO4. And the I/O buffer IOB3 isconnected to a device outside the module MDL2 through a signal linegroup L33.

According to the present invention, each circuit block communicates withexternal circuit blocks through micro-scale I/O circuits. Namely, in anyof the block diagrams shown in FIGS. 1 and 2, the block BLK1 isconnected to a micro-scale I/O circuit. In consequence, the same circuitblock BLK1 can be used to configure another chip/module with nomodification of the interface specifications related to power control.Accordingly, the number of man-hours for development of modules can bereduced significantly. This is effective even though the fineness offabrication is different between the chip CHP1 shown in FIG. 1 and thechip CHP3 shown in FIG. 2, because most of the necessary modificationsof a circuit block are due to a modification of fabrication.

For example, the circuit block BLK1 is assumed to have been developedfor the chip CHP3 shown in FIG. 2 fabricated in 0.18 μm CMOS processes.The circuit block BLK1 is assumed to be used for the chip CHP1 shown inFIG. 1 fabricated in 0.13 μm CMOS processes. This change of fineness offabrication increases the number of circuits to be integrated in a chipmore than before, consequently enabling both circuit blocks BLK1 andBLK2 to be mounted on the chip CHP1. In this case, however, anyadditional development for power control interface does not emerge.Therefore, the existing power control interface can be used for thecircuit block, because each circuit block is connected to anothercircuit block through a micro-scale I/O circuit, even when an existingcircuit block is diverted to another chip to develop a new chip. Thiscan minimize the modification of the circuit block to be required tocope with the fine-fabrication.

Furthermore, the circuit block might come to communicate with adifferent destination through the micro-scale I/O circuit, when thecircuit block is diverted to another chip. For example, the connecteddestination of the signal line group L31 differs between FIGS. 1 and 2.In FIG. 2, the signal line group L32 is connected finally to a deviceoutside the module MDL2 through the signal line group L31. In FIG. 1,however, the signal line group L32 is connected finally to the circuitblock BLK2 on the same chip CHP1 through the signal line group L31. Thismeans that a circuit block, when coming communicating with a differentdestination, can cope with the modified configuration only by connectingan I/O buffer, a mini-scale I/O buffer, or the like to the micro-scaleI/O circuit.

For example, when a destination is in another chip in the same module, amini-scale I/O buffer is preferable because this destination justrequires to driving a comparatively small load capacitance for thecommunication. On the other hand, while a destination is in anothermodule, an I/O buffer is preferable because this destination requires todriving a comparatively large load capacitance for the communication.Furthermore, when a destination is in the same chip, there is no needfor the I/O buffer or mini-scale I/O buffer, and otherwise, may use abuffer having smaller driving ability than the mini-scale I/O buffer.The micro-scale I/O circuit enables a buffer to be selected freelyaccording to the destination, thereby the interface operation is madefaster and the interface power consumption is reduced significantly.

FIG. 3 shows a basic configuration of the semiconductor integratedcircuit device of the present invention. Circuit blocks BLKA and BLKBare connected to each other through signal line groups LA and LB, aswell as through a micro-scale I/O circuit MIO. Generally, a circuitblock is defined as one that is configured by a group of circuits havingfunctions and is desirable to possibly be used by many modules. An IP(Intellectual Property: a circuit for executing such functions as anarithmetic function, a signal control function, etc. provided for asemiconductor integrated circuit) supplied by a so-called IP provideralso belongs to the circuit blocks.

A circuit block for which a micro-scale I/O circuit of the presentinvention should preferably be used is a unit grouped for a power supplycontrolling. For example, the circuit block BLKA enables a power supplyto be turned on/off independently of the state of the power to the wholechip. Where the circuit block BLKA power is turned off while the circuitblock BLKB is turned on, the signal line from the circuit block BLKA tothe circuit block BLKB goes into a floating state. In this case,assuming that the circuit blocks BLKA and BLKB are connected to eachother, a penetrating current adversely flows in the powered circuitblock BLKB. Using a micro-scale I/O circuit prevents the powered circuitblock BLKB from the adverse state, caused by controlling the power forthe circuit block BLKA.

In the above-mentioned example, the circuit block BLKB may also beformed so as to enable a power supply to be turned on/off independentlyof the state of power to the whole chip. The circuit blocks BLKA andBLKB may also operate on different supply voltages. Examples of suchcircuit blocks is: each of the I/O buffers IOB1, IOB2 and IOB3, as wellas the mini-scale I/O buffers MIOB1 and MIOB2 shown in FIGS. 1 and 2.

According to the present invention, the micro-scale I/O circuit is usedas an interface between the circuit blocks BLKA and BLKB. When thesupply voltage differs between the circuit blocks BLKA and BLKB, signalamplitude conversion is required (level conversion, hereafter) betweenthose BLKA and BLKB.

FIG. 4 shows a basic block diagram of the semiconductor integratedcircuit device of the present invention, which includes the micro-scaleI/O circuit provided with a level conversion circuit. In FIG. 4, VDDAand VSSA respectively denote a power supply and a ground of the circuitblock BLKA; VDDB and VSSB respectively denote a power supply and aground of the circuit block BLKB. Note that, because a supply voltage toa circuit is defined by both a high potential and a low potential, inthis embodiment, the power supply represents the high potential and theground represents the low potential. The signal lines d1 and d3represent one bit of the signal line group between the circuit blocksBLKA and BLKB, respectively. Signals from the sending side circuit blockBLKA are output through the signal line d1 and inputted to the receivingside circuit block BLKB through the micro-scale I/O circuit MIO and thesignal line d3. The micro-scale I/O circuit is configured by twocircuits; the first stage of micro-scale I/O circuit MIOA driven betweenthe power supply VDDA and the ground VSSA and the second stage ofmicro-scale I/O circuit MIOB driven between the power supply VDDB andthe ground VSSB. The signal line d2 denotes a plurality of signal linesconnected between the first stage of micro-scale I/O circuit MIOA andthe second stage of micro-scale I/O circuit MIOB. The signal d1 having asignal amplitude (VDDA-VSSA) output from the circuit block BLKA isinputted to the first stage of micro-scale I/O circuit MIOA; the firststage of micro-scale I/O circuit MIOA inputs signals required for levelconversion to the second stage of micro-scale I/O circuit MIOB throughthe signal line group d2; and the second stage of micro-scale I/Ocircuit MIOB converts the above signal to a signal having a signalamplitude (VDDB-VSSB) and inputs the result to the circuit block BLKBthrough the signal line d3.

This configuration makes it possible to supply an optimal supply voltageto each circuit block, thereby enabling high-speed and yet energyefficient operating characteristics. For example, a circuit block suchas an I/O buffer, a mini-scale I/O buffer, a real time clock (RTC), aninterrupt processing circuit, a DRAM refresh circuit and a low-speed andlarge capacity memory may be configured to receive a comparatively highsupply voltage by using MOS transistors having a comparatively largeabsolute threshold voltage. This can suppress a DC current toeffectively reduce the power consumption in the circuit block. For, thepower consumption of these circuit blocks is mainly caused by such a DCcurrent as a sub-threshold leakage current due to their comparativelylow activation rate. On the other hand, a circuit block such as a CPU,an MPEG4 accelerator and a high-speed and small capacity memory may beconfigured to receive a comparatively low supply voltage by using MOStransistors having a comparatively small absolute threshold voltage.This can suppress a charging and discharging current to effectivelyreduce the power consumption of the circuit block. Thus, the powerconsumption is caused mainly by its charging and discharging currentflowing while the circuit block is operating.

The threshold voltage and the gate insulator thickness of the MOStransistors in each circuit block may be configured to depend on thesupply voltage and the operation speed of the circuit block. Note thatthe threshold voltage and the gate insulator thickness may be variedamong chips or modules.

Both configuration and operation of a micro-scale I/O circuit will nowbe described, assuming that the supply voltage differs between thecircuit blocks BLKA and BLKB as shown in FIG. 4. The normal operation ofthe micro-scale I/O circuit is assured when the micro-scale I/O circuitcan shut off a penetrating current to be caused by a floating statesignal input. There are the following four types of power supplyshut-off patterns.

(1) The power supplies to both the sending side circuit block BLKA andthe first stage of the micro-scale I/O circuit MIOA are shut off (thepotential supply to the VDDA or VSSA is shut off). This state isreferred to as the “first case of power control.”

(2) The power supply to the receiving side circuit block BLKB is shutoff (the potential supply to the VDDB or VSSB to the circuit block BLKBis shut off) while the power supply to the second stage of themicro-scale I/O circuit MIOB continues. This state is referred to as the“second case of power control.”

(3) The power supply to the sending side circuit block BLKA is shut off(the potential supply to the VDDA or VSSA to the circuit block BLKA isshut off) while the power supply to the first stage of the micro-scaleI/O circuit MIOA continues. This state is referred to as the “third caseof power control.”

(4) The power supplies to both of the receiving side circuit block BLKBand the second stage of the micro-scale I/O circuit MIOB are shut off(the potential supply to the VDDB or VSSB is shut off). This state isreferred to as the “fourth case of power control.”

In the fourth case of power control, the normal operation of themicro-scale I/O circuit is assured basically in the configuration shownin FIG. 4. This is because the power supplies to the receiving circuitblock BLKB and the second stage of the micro-scale I/O circuit MIOB areshut off, thereby no penetrating current flows in the receiving sidecircuit block BLKB nor second stage of the micro-scale I/O circuit MIOBregardless of whether the power supply to the sending side circuit blockBLKA continues or not. Hereinafter, a configuration of the micro-scaleI/O circuit will be described. The following configuration supports thefirst to third cases of power control.

The configuration shown in FIG. 5 assures the normal operation of themicro-scale I/O circuit in the first case of power control. This firstcase of power control occurs, for example, when a voltage regulator thatsupplies a potential VDDA, VSSA, VDDB and VSSB to a chip stops supplyingthe potential VDDA or VSSA. In the configuration shown in FIG. 5, asignal e is inputted to the second stage of the micro-scale I/O circuitMIOB from the receiving side circuit block BLKB. In the first case ofpower control, power supply to the first stage of the micro-scale I/Ocircuit MIOA is shut off, so that the signal line group d2, which isoutput from the first stage of the micro-scale I/O circuit MIOA, goesinto a floating state. The second stage of the micro-scale I/O circuitMIOB must thus be prevented from the penetrating current flow even whenthis floating state signal is inputted thereto.

To assure the normal operation of this micro-scale I/O circuit in FIG.5, therefore, the above signal e is inputted to the second stage of themicro-scale I/O circuit MIOB. The circuit block BLKB is thus required torecognize the shut-off of the potential VDDA or VSSA. For example, thecircuit block BLKB may include an item “potential VDDA or VSSA supplyshut-off is notified” or an item “the chip includes a plurality of modesand the potential VDDA or VSSA shut-off in a special mode” in itsspecifications. In the latter case, when the chip goes into the specialmode, the circuit block BLKB recognizes the shut-off of the potentialVDDA or VSSA. Namely, the receiving side circuit block BLKB detects theshut-off of the power supply to the sending side circuit block BLKA andthe first stage of the micro-scale I/O circuit MIOA and sends the signale so as to enable normal operation of the micro-scale I/O circuit.

The configuration shown in FIG. 6 assures the normal operation of themicro-scale I/O circuit not only in the first case of power control, butalso in the second case of power control. The second case of powercontrol occurs, for example, when the potential VDDB or VSSB supply tothe circuit block BLKB is shut off while the voltage regulator continuesthe supply of the potential VDDB or VSSB. In the configuration shown inFIG. 6, the VDDB is supplied to the circuit block BLKB directly whilethe ground potential is supplied to the BLKB through the power switchPSWB. The power switch PSWB is turned on/off by the power switchingcontroller circuit PSCB. The second case of power control occurs whenthe controller circuit PSCB turns off the power switch PSWB. When thissecond case of power control occurs, the signal line e goes into thefloating state. When the controller circuit PSCB turns off the powerswitch PSWB, this power-off state is notified to the second stage of themicro-scale I/O circuit MIOB through the signal line cr. The secondstage of the micro-scale I/O circuit MIOB, because it can detect thefloating state of the signal line e through this signal cr, can operatethe micro-scale I/O circuit normally.

The configuration shown in FIG. 7 assures the normal operation of themicro-scale I/O circuit not only in the first case of power control, butalso in the third case of power control. The third case of power controloccurs, for example, when the potential VDDA or VSSA supply to thecircuit block BLKA is shut off while the voltage regulator continues thesupply of the potential VDDA or VSSA. In the configuration shown in FIG.7, the VDDA is supplied to the circuit block BLKA directly while theground potential VSSA is supplied to the BLKA through the power switchPSWA. The power switch PSWA is turned on/off by the power switchingcontroller circuit PSCA.

The third case of power control occurs when the controller circuit PSCAturns off the power switch PSWA. When this third case of power controloccurs, the signal line d1 goes into a floating state. When thecontroller circuit PSCA turns off the power switch PSWA, this power-offstate is notified to the first stage of the micro-scale I/O circuit MIOAthrough the signal line cs. The first stage of the micro-scale I/Ocircuit MIOA, because it can detect the floating state of the signalline d1 through this signal line cs, can operate the micro-scale I/Ocircuit normally.

FIG. 8 shows a configuration of the micro-scale I/O circuit for assuringthe above normal operation even in the first, second, and third cases ofpower control. This configuration may be a combination of those shown inFIGS. 6 and 7. Therefore, description for details of this combinationwill be omitted here.

FIG. 9 shows a detailed configuration of the micro-scale. I/O circuitshown in FIG. 8. Reference symbol NAND1 denotes a 2-input NAND circuit;INV1 and INV2 denote inverter circuits; AND1 denotes a 2-input ANDcircuit and MP1 denotes a PMOS transistor; MN1 denotes an NMOStransistor; and LC1 denotes a level conversion circuit, which amplifiesor attenuates the amplitude of the input signal (d2, /d2) so as to matchthe amplitude (VDDA-VSSA) with that (VDDB-VSSB) of the supply voltage ofthe level conversion circuit LC1 and outputs the level converted signalto a node d4. The logical level of the signal output to the node d4 isthe same as that of the signal inputted as a node d2. The powerpotential VDDB is supplied to the level conversion circuit LC1 directlywhile the ground potential VSSB is supplied to the LC1 through the NMOStransistor MN1.

In the first case of power control, the NMOS transistor MN1 is turnedoff and the PMOS transistor MP1 is turned on when the signal e reachesthe low level. Consequently, the NMOS transistor MN1 is kept off evenwhen the signals d2 and /d2 go into the floating state respectively,thereby the level conversion circuit LC1 is prevented from a penetratingcurrent flow. As a result, the output level of the level conversioncircuit LC1 goes into the floating state while the PMOS transistor MP1controls the logical level of the node d4 at high level. The micro-scaleI/O circuit is thus operated normally.

In the second case of power control, the signal cr is driven to lowlevel to operate the micro-scale I/O circuit. The AND circuit AND1 isthus prevented from a penetrating current flow even when the signal egoes into the floating state. In addition, because the output level ofAND circuit AND1 is controlled at low level, the normal operation of themicro-scale I/O circuit is assured.

In the third case of power control, the signal cs is driven to low levelto prevent the NAND circuit NAND1 from a penetrating current flow evenwhen the signal line d1 goes into the floating state. Because the outputlevel of NAND circuit NAND1 is controlled at high level, the micro-scaleI/O circuit is assured for the normal operation.

FIG. 19 shows an example of a configuration of the level conversioncircuit LC1. The LC1 is a differential level conversion circuit thatreceives the signal d1 and a complementary signal /d1.

In the configurations shown in FIGS. 4 through 9, the circuit block BLKAuses one signal line d1 to send one bit information. So calledsingle-ended signals are used for communications. On the other hand,when dual-rail signals are used for communications (two signal lines areused to send one bit information; the circuit block BLKA uses the signald1 and the complementary signal /d1), the first stage of the micro-scaleI/O circuit MIOA is omitted. When such dual-rail signals are used forsuch communications such, the logic gate level circuit is configuredjust like a circuit formed by deleting the first stage of themicro-scale I/O circuit MIOA from the configuration shown in FIG. 9 andinputting the signal d1 as the signal /d2 and the complementary signal/d1 as the signal d2 to the level conversion circuit LC1. In thisconnection, the signal line cs is omitted here.

The input/output signals shown in FIG. 9 are thus summarized as shown inFIG. 10. The “*” denotes any level including the floating level. The “−”denotes the high or low level. Each of the power supply states (ON, OFF1and OFF2) of the sending side circuit block SND and receiving sidecircuit block RCV denotes the logical level of each subject signal lined1, e, cs and cr. The power supply state “ON” of a circuit block denotesa state in which potentials VDDA/VDDB and VSSA/VSSB are supplied. Thepower supply state “OFF1” of the circuit block denotes a state in whichthe potentials VDDA/VDDB and VSSA/VSSB are supplied and a power issupplied to the micro-scale I/O circuit (its first stage for the sendingside circuit block SND or its second stage for the receiving sidecircuit block RCV) while power supply to the circuit block is shut offby such means as a power switch PSWA/PSWB. The circuit block powersupply state “OFF2” denotes a state in which the VDDA/VDDB or VSSA/VSSBpotential supply is shut off.

Consequently, the power supply to the subject circuit block can be shutoff in any of the above first to fourth cases of power control, becausethe micro-scale I/O circuit can inhibit a penetrating current flowcaused by a node driven into the floating state if the micro-scale I/Ocircuit were not provided. Accordingly, even when a non-negligiblesub-threshold leakage current flows due to a small absolute thresholdvoltage of the MOS transistors of the circuit block and/or when anon-negligible gate tunnel leakage current flows due to the thin gateinsulation film of the MOS transistors, the unnecessary powerconsumption increased in the subject module by a leakage current can beminimized.

The threshold voltage and the gate insulation film thickness of the MOStransistors in the subject circuit block are not limited specifically.Those of the MOS transistors of each power switch are also not limitedspecifically. Each power switch must obtain a comparatively largeon-current and a comparatively small off-current satisfactorily bycontrolling the potential of its gate terminal. Accordingly, theabsolute threshold voltage of the power switch is preferable to behigher than that of the MOS transistors of the circuit block. And thegate insulation film thickness of the power switch also is preferable tobe thicker than that of the MOS transistors of the circuit block. Thegate insulation film thickness mentioned here is an effective gateinsulation film thickness to which the permittivity of the gateinsulation film's material is taken into consideration.

In the configuration shown in FIG. 9, although a ground potential issupplied to the level conversion circuit LC1 through the NMOS transistorMN1, another configuration is possible. The level conversion circuit LC1may have a configuration, in which instead of the NMOS transistor MN1, aPMOS transistor may be inserted between the power supply VDDB and thelevel conversion circuit LC1, and the PMOS transistor is turned off inthe first case of power control.

In the configurations shown in FIGS. 6 through 8, the NMOS transistorPSWA or NMOS transistor PSWB is disposed between the subject circuitblock and the ground line so that the transistor functions as a powerswitch between them to realize the second or third case of powercontrol. On the other hand, a PMOS transistor may be disposed betweenthe circuit block and the power line so that the transistor functions asa power switch between them.

All of the first to fourth cases of power control are not necessarilyprovided and any of them may be provided selectively in accordance withthe chip or module specifications. When the first case of power controlis not provided, the AND circuit AND1 may be replaced with a buffercircuit, so that the signal line cr is buffered, then inputted to thegate terminals of the NMOS transistor MN1 and the PMOS transistor MP1directly. When the second case of power control is not provided, the ANDcircuit AND1 may be replaced with a buffer circuit, so that the signalline e is buffered, then inputted to the gate terminals of the NMOStransistor MN1 and the PMOS transistor MP1 directly. When the third caseof power control is not provided, the NAND circuit NAND1 may be replacedwith an inverter circuit, so that the signal line d1 is inverted, theninputted to the signal line /d2 directly. In addition to the abovecases, the cases of power control may be combined freely.

In FIGS. 4 through 9, single-bit signals are sent or received betweencircuit blocks so as to make it easier to understand. Usually, however,signal lines are used to send or receive a plurality of signals betweenthose circuit blocks. In this case, control signals e, cr, and cs arerequired to control the plurality of signal lines. There is no need toprovide these control signals for each bit. Each circuit block canusually send and receive signals and the circuit blocks are divided intosending side ones and receiving side ones just to make it easier tounderstand. Further, while a differential level conversion circuit isused in FIGS. 4 through 9, it may be replaced with an inverter typelevel-down circuit. In addition, the level conversion circuit may beomitted if the operation voltage is the same among the circuit blocks.Each circuit can thus be modified freely according to the whole chip ormodule specification.

Embodiment 2

FIG. 11A shows a block diagram of an interface of a power switchingcontroller circuit PSCA or PSCB shown in FIGS. 6 through 8. FIG. 11B isa timing diagram for FIG. 11A. A power switching controller circuit PSCfor controlling the power switch PSW controls the on/off state of thepower switch PSW through the hand-shaking of a request line req and anacknowledge line ack to control the power supply to each circuit blockBLK. In FIGS. 11A and B, the request line req is driven high level attime T1 to turn on the power switch PSW and supply a power to thesubject circuit block BLK. When the power switch PSW is turned on andthe power supply to the circuit block BLK is completed, the acknowledgeline ack is driven high level at time T1B to notify the subject deviceoutside the power switching controller circuit PSC that the circuitblock BLK is ready to operate. On the other hand, the request line reqis driven low level at time T2 to turn off the power switch PSW and shutoff the power to the circuit block BLK. When the turning off of thepower switch PSW is completed, the acknowledge line ack is driven lowlevel at time T2B to notify the subject device outside the powerswitching controller circuit PSC that the power to the circuit block BLKis shut off.

In FIG. 8, the power switching controller circuit outputs a power on/offstate signal to the corresponding micro-scale I/O circuit through asignal line cs or cr. In the configuration shown in FIG. 11A and thetiming diagram of FIG. 1B, the signal line c is equivalent to any ofthose signal lines cs and cr. The signal line c can establish a setstate more quickly than the acknowledge line ack. For example, beforethe acknowledge line ack is driven high level, the signal line c isdriven high level at time T1A. And, before the acknowledge line ack isdriven low level, the signal line c is driven low level at time T2A.Thus, the signal line c establishes a set state more quickly than theacknowledge line ack. The communication between circuit blocks willmalfunction if the micro-scale I/O circuit was not ready to operate whenthe circuit block BLK is ready to receive/output a signal after thepower switch PSW is turned on/off. To avoid this, the signal c should beused to control the micro-scale I/O circuit so that it gets ready tooperate before the acknowledge line ack is driven high level.

While each circuit block is grounded through a power switch in the abovedescription, when no problem arises from the DC power consumption causedby a leakage current, there is no need to shut off the power supply bythe power switch. This, for example, corresponds to the case where anI/O buffer includes transistors that operate at a high voltage and havea comparatively thick gate insulation film respectively. Further, somecircuit blocks includes transistors having a high absolute thresholdvoltage respectively do not face the DC power consumption problem. Inthese cases, there is no need to ground each circuit block through apower switch as described above. Whether to use a power switch to shutoff a power is determined by the configuration of MOS transistors in thesubject circuit block and/or the characteristics of the subject circuitof the circuit block.

Nevertheless, a power switch can suppress the transmission of the noisegenerated in a circuit block to another through the ground. In short,grounding through the power switch prevents the transmission of thenoise through the ground. This is because the power switch thatfunctions as a resistor to form a low-pass filter with a capacitance,such as each circuit block parasitic capacitance and the ground lineparasitic capacitance. For example, the circuit block BLKA is assumed tobe a digital circuit that employs a high-speed operation and the circuitblock BLKB is assumed to be an analog circuit as an A/D converter thatemploys a high precision operation.

Further, the relationship between the power supplies VDDA and VDDB isassumed to be VDDA<VDDB, since a supply voltage applied to the digitalcircuit is usually lower than that of the analog circuit. The groundsVSSA and VSSB are usually connected to each other in the subject chip oroutside the module. In this connection, because the supply voltagediffers between the power supplies VDDA and VDDB and the power suppliesare separated even outside the module, very little noise generated inthe power supply VDDA is transmitted to the power supply VDDB. Becausethe grounds VSSA and VSSB are connected to each other, however, thenoise by the digital circuit is transmitted directly to the analogcircuit if no power switch is provided.

On the other hand, when a power switch is provided in the configurationlike in FIG. 8, the noise generated by the digital circuit is attenuatedby the power switch PSWA and transmitted to the grounds VSSA and VSSB.The noise in the grounds VSSA and VSSB is further attenuated by thepower switch PSWB and transmitted to the virtual ground line VSSMB,which is an actual ground line of the analog circuit. Consequently, thenoise coupling between the digital circuit and the analog circuit can bereduced.

Embodiment 3

The substrate terminal (well) of each MOS transistor of a circuit blockis connected according to its object characteristics in various ways.FIG. 12 shows a block diagram of a circuit block in which the substrateterminal vbp of the PMOS transistor MP2 is connected to the power supplyVDD and the substrate terminal vbn of the NMOS transistor MN2 isconnected to the ground VSS. Connecting the well vbn of the NMOStransistor MN2 to the ground VSS in such a way allows the potential ofthe virtual ground line VSSM to rise when the power switch PSW is turnedoff. This also allows the reversed substrate bias voltage to be appliedbetween the source of the NMOS transistor MN2 and the substrate (well).Accordingly, the leakage current that flows through the NMOS transistorMN2 is reduced due to the substrate bias effect. Otherwise, thesubstrate terminal vbn may be connected to the virtual ground line VSSM.Because the well potential of the NMOS transistor MN2 and the sourcepotential become equal, this connection is more suitable increasing thespeed of the transistor operation.

In the configuration shown in FIG. 13, a substrate voltage controllercircuit VBC is used to control the potentials of the substrate terminalvbp of the PMOS transistor MP2 and the substrate terminal vbn of theNMOS transistor MN2 in a circuit block. Although the vbp and vbnpotentials are not limited specifically, a low voltage, that is VDD orlower potential than VDD, may be applied to the well vbp and a highvoltage, that is VSS or higher potential than VSS, may be applied to thewell vbn to increase the speed of the circuit block BLK operation. Inaddition, an optimal potential may also be applied to both wells vbp andvbn according to the operation speed required for the circuit block BLK.In particular, determining the potentials to be applied to both vbp andvbn according to the process, temperature, or supply voltage of thecircuit block can compensate for the process variation or thetemperature/supply voltage variation.

Note that while a configuration of the inverter circuit in the circuitblock BLK is shown in FIGS. 12 and 13, it is just a typical example ofthe CMOS logic circuit, and the configuration can be applied to variousother circuits.

Embodiment 4

A circuit block layout will now be described. FIG. 14 shows a layout ofthe circuit block BLK shown in FIG. 12. RUSR denotes a circuit block BLKarea in which MOS transistors are disposed. A ring-like area is formedby areas RPWR1 to RPWR8 where power supply rings correspond to powersupply lines such as the power line VDD, the ground line VSS, thevirtual ground line VSSM, etc. shown in FIG. 12 are disposed.Comparatively wide wires form these power supply rings. Consequently,the power line, the ground line and the virtual ground line connected tothe MOS transistors in the circuit block have low resistance,respectively.

The power switches PSW should preferably be disposed in each of the fourside areas, that is areas RPWR2, RPWR4, RPWR6 and RPWR8, of thering-like area respectively. In particular, the power switches PSWshould desirably be disposed in the areas RPWR4 and RPWR8 respectively.As shown in FIG. 15, the power line VDD105(M1) and the virtual groundline VSSM105(M1) for the standard cell CELL of the circuit block areextended horizontally. This allows a power switches PSW disposed in eachof the areas RPWR4 and RPWR8 to reduce the influence from the wiringresistance. On the other hand, the power switches PSW disposed in eachof the areas RPWR2 and RPWR6 increases the influence from the wiringresistance of the virtual power line and the virtual ground linedisposed in each of the areas RPWR4 and RPWR8. The power switches PSWshould be desirably disposed in the areas RPWR4 and RPWR8 by priority,therefore, then additional power switches PSW should be disposed in theareas RPWR2 and RPWR6 to reduce the influence further from theon-resistance of the power switches PSW. The power switching controllercircuit PSC shown in FIG. 12 and the substrate bias controller circuitVBC shown in FIG. 13 may be disposed in some of the four corner areas ofthe ring-like area, that is at least one of areas RPWR1, RPWR3, RPWR5 orRPWR7. The larger the scale of the circuit block, the larger the sizeoccupied by the circuit block. This means that the sizes of the areasRPWR2, RPWR4, RPWR6 and RPWR8 also expand. Accordingly, the powerswitches PSW can thus be disposed so that the gate width of the powerswitches PSW satisfies the scale of the subject circuit block. On theother hand, the sizes of the areas RPWR1, RPWR3, RPWR5 and RPWR7 can bedetermined independently of the size occupied by the subject circuitblock. Also in this connection, the power switching controller circuitPSC and the substrate bias controller circuit VBC shown in FIG. 13should desirably be disposed in each of the four corner areas of thering-like area.

FIG. 15 shows an expanded view of the portion R14 shown in FIG. 14, inwhich the power line VDD, the ground line VSS and the virtual groundline VSSM are disposed. VDD100 to VDD110 denote power lines, VSS101 toVSS103, as well as VSS107 to VSS113 denote ground lines and VSSM101 toVSSM107 denote virtual ground lines. SIG100 denotes one of the linescrossing the power supply ring vertically. SIG101 denotes one of thelines crossing the power supply ring horizontally. The symbols M1 to M4described in the parentheses following each symbol in FIG. 15 denote awiring layer used to dispose the line. A plurality of symbols denotethat lines are disposed in a plurality of wiring layers. Layer M4 isdisposed above layer M3, layer M3 is disposed above layer M2, and layerM2 is above layer M1. A square with symbol x denotes via hole forconnecting each wiring layer. Portion RPWP denotes the ring-like areafor power supply rings. Portion RUSR denotes an area in which MOStransistors of the subject circuit block are disposed.

The power supply rings include lines VDD101 to VDD103, VSS101 to VSS103,VSSM101 to VSSM103 and VSSl11 to VSS113 in the wiring layers M2 to M4,which are comparatively upper layers from the semiconductor substrate.Because upper wiring layers enable wiring pitches to be secured morewidely, upper wiring layers can be formed more thickly; thereby thesheet resistances of wirings can be reduced in size and low resistancewirings are realized. Such low resistance wirings in the power supplyrings make it possible to form the power supply ring with lowresistance, thereby the so-called voltage drop is suppressed.

In FIG. 15, a vertical power line RPWRV that shunts the power supplyrings is formed vertically with both lines VDD106 and VSSM106. Ahorizontal power line RPWRH that shunts the power supply rings is formedhorizontally with lines VDD107, VSS107 and VSSM107. Consequently, thepower supply ring functions as a further low resistor. Although thevertical disposition pitches of the vertical power lines RPWRV and thevertical disposition pitches of the horizontal power supply lines RPWRHare not limited specifically. The number of channels for wiring signallines of the MOS transistors of a circuit block is reduced if thevertical power supply lines RPWRV were disposed excessively, becauseboth vertical power supply lines RPWRV and many signal lines should bedisposed in the wiring layer M2. To avoid this, therefore, the verticalpower lines RPWRV should be appropriately disposed at about 100 μmpitches. Incidentally, the comparatively upper wiring layer M4 is usedfor disposing the horizontal power supply lines RPWRH, there is littlepossibility to reduce the number of channels for wiring the signallines. So, many horizontal power supply lines RPWRH can be disposed.

The power supply lines RCELL include lines VDD105 and VSSM105 formed inthe wiring layer M1, which supplies supply voltage from the power supplyring to the MOS transistors of each circuit block. When many standardcells CELL100 are disposed side by side to configure a circuit, thepower supply lines RCELL are disposed vertically at the same dispositionpitches as those of the standard cells CELL100 so that a power issupplied to all the standard cells CELL100. Channels used for wiringsignal lines of the MOS transistors of the circuit block are usuallydisposed in the wiring layers M1 to M3. Similarly, in the four cornerareas of the ring-like area, the power and ground lines are disposed inthe wiring layer M4; no lower wiring layers are used. When the powerswitching controller circuit PSC or the substrate bias controllercircuit VBC are provided, a sufficient number of wiring layers M1 to M3are used to configure the target circuit. When none of the circuits PSCand VBC is used, those wiring layers can be used for the power andground lines.

Lines VDD109, VDD110, VSS109 and VSS110 are used to supply powers andground potentials to the power supply ring from external power supplyring. Because the wiring layers M4 and M1 are used for the above supplylines, the wiring layers M2 and M3 can be used for wiring signal linesbetween each circuit block and the micro-scale I/O circuit such as linesSIG100 and SIG101.

While only one line VDD108 for connecting line VDD100 to line VDD103electrically is shown in FIG. 15 to make it simplify the description,many lines VDD108 should actually be disposed at certain pitches toreduce the connection resistance. Although no vertical electricalconnection of the lines VDD100 and VDD101 is shown in FIG. 15, theyshould desirably be wired in the wiring layer M2 just like the lineVDD108. While only one line VSS108 for connecting line VSS103 to lineVSS113 is shown in FIG. 15 to make it simplify the description, manylines VSS108 should actually be disposed at certain pitches to reducethe connection resistance. While vertical electrical connection of thelines VSS101 and VSSl11 is not shown in FIG. 15, the lines VSS101 andVSS111 should desirably be disposed in the wiring layer M3 just like theline VSS108.

The above layout thus makes it possible to use wiring layers efficientlyto supply a low impedance power to the standard cells CELL100. AlthoughFIG. 15 shows a configuration including four wiring layers, more wiringlayers may be included. In this connection, the more wiring layers canbe used in the configuration shown in FIG. 15 to configure a lowerresistance power supply ring. Although how to use those wiring layersconcretely is not limited, the top wiring layer (layer M4 in FIG. 15)and the bottom wiring layer (layer M1 in FIG. 15) should be used tosupply both power and ground potential to the power supply ring fromexternal, because many wiring layers can thus be used efficiently todispose signal lines between each circuit block and its micro-scale I/Ocircuit. In addition, the horizontal power supply lines RPWRH should bedisposed in the top wiring layer (layer M4 in FIG. 15). This is becausemany channels for wiring signal lines of the MOS transistors in thesubject circuit block can be secured.

Embodiment 5

FIG. 16 shows a cross sectional view of a chip of the present invention.PSUB100 denotes a P-type substrate. NW100 and NW110 denote N-type wells.PW100 and PW110 denote P-type wells. NIS0100 and NIS0110 denote impuritylayers formed more deeply than the wells NW100 and NW110, that is,so-called deep N-type wells used to configure a triple well structure.P100 and P101 denote P-type diffusion layers, which form a PMOStransistor MP100 with a gate electrode G100 and a gate insulation filmT100. P110 and P111 are also P-type diffusion layers, which form a PMOStransistor MP110 with a gate electrode G110 and a gate insulation filmT110. N100 and N101 denote N-type diffusion layers, which form an NMOStransistor MN100 with a gate electrode G101 and a gate insulation filmT101. N110 and N111 are also N-type diffusion layers, which form an NMOStransistor MN110 with a gate electrode G111 and a gate insulation filmT111. N102 denotes an N-type diffusion layer; it is a substrate terminalof the PMOS transistor MP100 used to supply a potential to the N-typewell NW100. P102 denotes a P-type diffusion layer; it is a substrateterminal of the NMOS transistor MN100 used to supply a potential to theP-type well PW100. N112 denotes an N-type diffusion layer; it is asubstrate terminal of the PMOS transistor MP110 used to supply apotential to the N-type well NW110. P112 denotes a P-type diffusionlayer; it is a substrate terminal of the NMOS transistor MN110 used tosupply a potential to the P-type well PW110. S100 denotes a P-typediffusion layer from which a potential is supplied to the PSUB100.

The employment of the triple well structure makes it possible to set thepower supply potential and the ground potential independently of eachother in each circuit block. For example, in the configuration shown inFIG. 4, MOS transistors MP100 and MN100 of the circuit block BLKA areformed on a deep N-type well NIS0100 respectively. MOS transistors MP100and MN110 of the circuit block BLKB are formed on a deep N-type wellNIS0110 respectively. Because the substrate potential of MOS transistorscan be set in each circuit block independently of those in other circuitblocks, the configuration shown in FIG. 13 is realized.

FIG. 17 shows a layout example of the configuration shown in FIG. 4. Inorder to simplify the description, FIG. 17 shows only the layout of thedeep N-type well shown in FIG. 16. NISOBLKA denotes a deep N-type wellof the circuit block BLKA. NISOBLKB denotes a deep N-type well of thecircuit block BLKB. NISOMIOAL to NISOMIOA3 denote deep N-type wells ofthe first stage of micro-scale I/O circuit MIOA. NISOMIOB1 to NISOMIOB3denote deep N-type wells of the second stage of micro-scale I/O circuitMIOB. The deep N-type well NISOBLKA has the same potential (VDDA) asthat of the deep N-type wells NISOMIOA1 to NISOMIOA3, so that thosewells can be connected to each other. The deep N-type well NISOBLKB hasthe same potential (VDDB) as that of the deep N-type wells NISOMIOB1 toNISOMIOB3, so that those wells can be connected to each other. TheP-type diffusion layer S100 may be formed between the deep N-type wellNISOMIOA1 to NISOMIOA3 and the deep N-type well NISOMIOB1 to NISOMIOB3.This reduces the mutual interference of the noise generated in thecircuit blocks BLKA and BLKB.

Embodiment 6

FIG. 18 shows a configuration of the micro-scale I/O circuit of thepresent invention, provided with a scanning function. This configurationaims to test the subject circuit block easily. In FIG. 18, BLKA denotesa sending side circuit block and BLKB denotes a receiving side circuitblock. MIOb1 to MIObn denote respective one bits of micro-scale I/Ocircuit. LA1 to LAn denote respective input signals to the micro-scaleI/O circuit. LB1 to LBn denote output signals from the micro-scale I/Ocircuit. In order to simplify the description, such control signals cr,cs, e, etc., as well as power related connections as shown in FIG. 8 areomitted here. A scanned data input is denoted by siφ. The data isshifted sequentially in order of si1, si2, sin, . . . .

Generally, a flip-flop (FF) is scanned when its inside state is to beset forcibly from outside the subject chip. In this case, the input datafrom the si0 is used forcibly to set the outputs LB1 to LBn of thesubject micro-scale I/O circuit; the inputs LA1 to LAn to themicro-scale I/O circuit are neglected here. Although the concreteconfiguration of the micro-scale I/O circuit is omitted here, theconfiguration is realized, for example, by providing a flip-flop themicro-scale I/O circuit and a plurality of micro-scale I/O circuits areconnected to form a shift register. Using this scanning path makes itpossible to output the values of the inputs LA1 to LAn to sinsequentially in order of LAn to LA1. With use of the scanning functionprovided for each micro-scale I/O circuit, the function tests of eachcircuit block can be executed easily and quickly.

While the preferred embodiments of the present invention have beendescribed concretely, it is to be understood that modifications will beapparent to those skilled in the art without departing from the spiritof the present invention.

The present invention can thus obtain the following effects. The numberof man-hours required for the development of each chip or module can bereduced. Circuit modification to be required by a change of afabrication process can be minimized. The optimized power supply can besupplied to each circuit block, thereby the device operation speed isincreased and the device power consumption is reduced at the same time.Power supply to each circuit block can be shut off by various means whenthe circuit block is idle, thereby unnecessary power consumption causedby a leakage current is reduced.

While the present invention has been described above in connection withthe preferred embodiments, one of ordinary skill in the art would bemotivated by this disclosure to make various modifications and still bewithin the scope and spirit of the present invention as recited in theappended claims.

1. A semiconductor integrated circuit device, comprising: a firstcircuit block to which a first supply voltage is to be applied, thefirst supply voltage being defined by first operating points; afirst-stage intermediate circuit to which the first supply voltage is tobe applied, and which receives an output of the first circuit block; asecond-stage intermediate circuit to which a second supply voltage is tobe applied, and receiving an output of the first-stage intermediatecircuit, the second supply voltage being defined by second operatingpoints; and a second circuit block to which the second supply voltage isto be applied and which receives an output of the second-stageintermediate circuit, wherein the second circuit block outputs afirst-state first control signal to the second-stage intermediatecircuit when the first supply voltage is applied to the first circuitblock and the first-stage intermediate circuit so that the output of thesecond-stage intermediate circuit changes in state according to a changein the output of the first circuit block, and wherein the second circuitblock outputs a second-state first control signal to the second-stageintermediate circuit when the first supply voltage is not applied to thefirst circuit block and the first-stage intermediate circuit so that thesecond-stage intermediate circuit controls its output to a potential ofone of the second operating points.
 2. The semiconductor integratedcircuit according to claim 1, further comprising: a first MOStransistor, the first supply voltage being applied to the first circuitblock through the first MOS transistor; and a first controlling circuitwhich controls a state of the first MOS transistor, wherein the firstcontrolling circuit outputs a first-state second control signal to thefirst-stage intermediate circuit when the first MOS transistor is to bein an ON state so that the output of the first-stage intermediatecircuit is changed in state according to a change of the output of thefirst circuit block, and wherein the first controlling circuit outputs asecond-state second control signal to the first-stage intermediatecircuit when the first MOS transistor is to be in an OFF state so thatthe first-stage intermediate circuit controls its output to a potentialof one of the first operating points.
 3. The semiconductor integratedcircuit device according to claim 1, further comprising: a second MOStransistor, the second supply voltage being applied to the secondcircuit block through the second MOS transistor; and a secondcontrolling circuit which controls a state of the second MOS transistor,wherein the second controlling circuit outputs a first-state thirdcontrol signal to the second-stage intermediate circuit when the secondMOS transistor is to be in an ON state so that an input of thesecond-stage intermediate circuit is to be changed in state according toa change of the output of the second circuit block, and wherein thesecond controlling circuit outputs a second-state third control signalto the second-stage intermediate circuit when the second MOS transistoris to be in an OFF state so that the second-stage intermediate circuitcontrols its input to be at a potential of one of the second operatingpoints.
 4. The semiconductor integrated circuit device according toclaim 1, wherein the first supply voltage and the second supply voltageare different from one another, and wherein the second-stageintermediate circuit includes a level conversion circuit.
 5. Thesemiconductor integrated circuit device according to claim 1, wherein athreshold voltage of a MOS transistor of the first circuit block isdifferent from a threshold voltage of a MOS transistor of the secondcircuit block.
 6. The semiconductor integrated circuit device accordingto claim 2, wherein the first controlling circuit outputs a fourthcontrol signal to an external circuit block, and wherein the secondcontrol signal is shifted from the second-state to the first-state,before the fourth control signal is shifted from a first-state, whichindicates that the first circuit block has disabled input/output, to asecond-state, which indicates that the first circuit block has enabledinput/output.
 7. The semiconductor integrated circuit device accordingto claim 3, wherein the second controlling circuit outputs a fifthcontrol signal to an external circuit block, and wherein the thirdcontrol signal is shifted from the second-state to the first-state,before the fifth control signal is shifted from a first-state, whichindicates that the second circuit block has disabled input/output, to asecond-state, which indicates that the second circuit block has enabledinput/output.
 8. The semiconductor integrated circuit device accordingto claim 3, wherein the first circuit block is formed on a first deepwell, wherein the second circuit block is formed on a second deep wellhaving the same conductivity type as the first deep well, wherein thefirst intermediate circuit is formed on a third deep well having thesame conductivity type as the first deep well, wherein the secondintermediate circuit is formed on a fourth deep well having the sameconductivity type as the first deep well, and wherein the first, second,third and fourth deep wells are separated from each other by pnjunctions.
 9. A semiconductor integrated circuit device, comprising: afirst circuit block; a second circuit block having operating potentials;and a first intermediate circuit which connects the first circuit blockto the second circuit block, wherein the first circuit block has a firstmode for enabling application of a supply voltage and a second mode fordisabling application of the supply voltage, and wherein the firstintermediate circuit controls a potential of an input node of the secondcircuit block to be any one of the operating potentials of the secondcircuit block when the first circuit block is in the second mode. 10.The semiconductor integrated circuit device according to claim 9,further comprising: a third circuit block having operating potentials;and a second intermediate circuit which connects the first circuit blockto the third circuit block, wherein the second intermediate circuitcontrols a potential of an input node of the third circuit block to beany one of the operating potentials of the third circuit block when thefirst circuit block is in the second mode.
 11. The semiconductorintegrated circuit device according to claim 10, wherein each of thefirst intermediate circuit and the second intermediate circuit has acommon supply power control interface.
 12. The semiconductor integratedcircuit device according to claim 9, wherein the supply voltage of thefirst circuit block differs from a supply voltage of the second circuitblock.
 13. The semiconductor integrated circuit device according toclaim 12, wherein the first intermediate circuit includes a levelconversion circuit.
 14. The semiconductor integrated circuit deviceaccording to claim 9, wherein the second circuit block is aninput/output buffer.
 15. A semiconductor integrated circuit deviceenabling reuse of circuit blocks having an interface for predeterminedsupply voltage control, the semiconductor integrated circuit devicecomprising: a first circuit block; a second circuit block; and a firstintermediate circuit which connects the first circuit block to thesecond circuit block according to the predetermined supply voltagecontrol, wherein the first circuit block of the semiconductor integratedcircuit device has a first mode for enabling application of a supplyvoltage and a second mode for disabling application of the supplyvoltage, wherein the first intermediate circuit controls a potential ofan input node of the second circuit block to any one of the operatingpotentials of the second circuit block when the first circuit block isin the second mode, and wherein the first circuit block can be connectedto the second circuit block without requiring modification of circuitconfigurations of the first circuit block or the second circuit blockfor supply voltage control purposes.
 16. The semiconductor integratedcircuit device according to claim 15, further comprising: a thirdcircuit block having operating potentials; and a second intermediatecircuit which connects the first circuit block to the third circuitblock according to the predetermined supply voltage control, wherein thesecond intermediate circuit controls a potential of an input node of thethird circuit block to be any one of the operating potentials of thethird circuit block when the first circuit block is in the second mode,and wherein the first circuit block can be connected to the thirdcircuit block without requiring modification of circuit configurationsof the first circuit block or the third circuit block for supply voltagecontrol purposes.
 17. The semiconductor integrated circuit deviceaccording to claim 16, wherein the supply voltage of the first circuitblock differs from a supply voltage of the second circuit block.
 18. Thesemiconductor integrated circuit device according to claim 17, whereinthe first intermediate circuit includes a level conversion circuit. 19.The semiconductor integrated circuit device according to claim 15,wherein the second circuit block is an input/output buffer.
 20. Asemiconductor integrated circuit device, comprising: a first area havinga first side extending in a first direction and a second side extendingin a second direction that crosses the first direction, the first areahaving formed therein a first MOS transistor of a circuit block; asecond area having a third side extending in the first direction and afourth side extending in the second direction, the second area beingdisposed so that the third side is adjacent to the first side; a thirdarea having a fifth side extending in the first direction and a sixthside extending in the second direction, the third area being disposed sothat the sixth side is adjacent to the second side; and a fourth areahaving a seventh side extending in the first direction and an eighthside extending in the second direction, the fourth area being disposedso that the seventh side is adjacent to the fifth side and the eighthside is adjacent to the fourth side, wherein first, second and thirdpower lines are disposed in wiring layers of the second to fourth areas,wherein fourth and fifth power lines disposed in the lowest wiring layerof the first area are extended in the second direction, the fourth andfifth power lines applying a supply voltage to the first MOS transistor,wherein the first and fourth power lines are connected to each otherelectrically, wherein the third and fifth power lines are connected toeach other electrically, wherein the second and third power lines areconnected to each other through a plurality of second MOS transistors,and wherein the plurality of second MOS transistors are disposed in thesecond area.
 21. The semiconductor integrated circuit device accordingto claim 20, wherein the plurality of second MOS transistors aredisposed in the third area.
 22. The semiconductor integrated circuitdevice according to claim 20, wherein a controlling circuit is providedin the fourth area, the controlling circuit controlling the ON/OFF stateof the second MOS transistor.
 23. The semiconductor integrated circuitdevice according to claim 20, wherein the first to third power lines areextended in the first direction in the second area, bent in the fourtharea, and extended in the second direction in the third area.